Movable and tiltable bearing, especially for bridges

ABSTRACT

The present movable and tiltable bearing is suitable for supporting heavy loads, such as bridges, by means of an elastically yielding pressure cushion, for example, made of rubber, which is surrounded by retaining ring means. In one embodiment one ring encircles the cushion middle portion to leave gaps above and below the ring. In another embodiment two rings are provided, one inside an annular cushion, the other outside of the annular cushion. Two rings are also used to surround a top and bottom region of a cushion whereby to leave a gap between these rings to permit the tilting movement.

United States Patent Koester et al.

[ Jan. 1,1974

MOVABLE AND TILTABLE BEARING, ESPECIALLY FOR BRIDGES Inventors: WaldemarKoester, Forsbach,

Germany; Reinhold Huber, Rorbas, Switzerland Assignee: Kober AG, Glarus,Switzerland Filed: Dec. 21, 1971 Appl. No.: 210,439

Foreign Application Priority Data Dec. 24, 1970 Germany P 20 63 745.0Mar. 26, 1971 Germany P 21 14 662.3

ms. c1. 308/3 R, 14/16 Int. Cl. Fvl6c 27/06 Field of Search 308/3 R:277/180;

References Cited UNITED STATES PATENTS Olson 277/l80 10/1967 Hein 308/3R 12/1970 Price et al 308/3 R Primary Examiner-Charles J. MyhreAssistant ExaminerBarry Grossman Attorney-Wolfgang G. Fasse [5 7]ABSTRACT The present movable and tiltable bearing is suitable forsupporting heavy loads, such as bridges, by means of an elasticallyyielding pressure cushion, for example, made of rubber, which issurrounded by retaining ring means. In one embodiment one ring encirclesthe cushion middle portion to leave gaps above and below the ring. Inanother embodiment two rings are provided, one inside an annularcushion, the other outside of the annular cushion. Two rings are alsoused to surround'a top and bottom region of a cushion whereby to leave agap between these rings to permit the tilting movement.

1 16 Claims, 15 Drawing Figures MOVABLE AND TILTABLE BEARING, ESPECIALLYFOR BRIDGES BACKGROUND OF THE INVENTION The invention relates to amovable and tiltable bearing, especially for heavy loads such as bridgesor similar supporting structures, wherein a pressure cushion havingrubber-elastic characteristics is arranged between an upper and lowersupporting or bearing surface of the supporting structure.

Such bearing means are known as so called rubber bearings or elastomericbearings. The elastic resiliency of the elastomer permits horizontalmovements and tilting movements in all directions to a limited degree.In order to prevent that the elastomer, for example in the form of aplate-shaped pressure cushion, which is mostly polygonal or circular, issqueezed out laterally by the load, prior art constructions havereinforced the pressure cushion by strengthening means such as steelplates or synthetic sheets or layers strengthened by fibers. Thisconstruction resulted in an areal bearing which is practicallyunyieldable in the vertical direction due to the reinforcement forpreventing the lateral escaping or yielding of the pressure cushionmaterial. However, tilting movements and horizontal displacements of theupper bearing surface relative to the lower bearing surface of thesupporting structure are possible. The sum of the thicknesses of allrubber layers determines the capacity of the bearing for the horizontaldisplacement and the tilting movement, since the strengthening means arenot deformable.

Another prior art tiltable bearing has a pressure cushion surrounded atits circumference by a plurality of rings which are supposed to preventor substantially limit transverse expansions of the pressure cushionunder loads. Such bearing has been disclosed in German publishedapplication No. 1,803,312 wherein the reinforcing inserts inside of thepressure cushion have been replaced by rings, thus avoidingnon-permissably high tensile forces at said reinforcing insert. Thetotal height of this known pressure cushion is selected in accordancewith the desired tiltability and movability. An increase of thetiltability by increasing the height of the pressure cushion, resultssimultaneously in an increase in the horizontal displaceability.

In many instances, it is desirable that these bearings should be highlytiltable while simultaneously having a small horizontal displaceability.

OBJECTS OF THE INVENTION The invention aims at achieving the followingobjects singly or in combination:

to overcome or alleviate the drawbacks of heretofore known movable andtiltable bearings, especially for bridges and similar supportingstructures;

to provide a bearing which, although small in height,

is characterized by a high tiltability and a comparatively lowhorizontal displaceability; and

to construct these bearings so that they are rather stiff againsthorizontal displacement.

SUMMARY OF THE INVENTION According to the invention, the pressurecushion is circumferentially enclosed by one or two rings such that thetotal height of the non-enclosed circumferential area of the pressurecushion is large enough to assure the desired tiltability, butsimultaneously small enough to limit the horizontal displaceability. Asa rough guide for dimensioning the present bearing, the circumferentialarea of the cushion enclosed by the ring or rings should have a heightgreater than one half of the height of the pressure cushion. In otherwords, the ring or rings should have a height corresponding to more thanone half of the pressure cushion height.

According to one example embodiment of the invention, the pressurecushion is surrounded by a ring which rests against its circumferentialsurface and which is freely movable and spaced from the supportingbearing surface whereby the ring is held by the pressure cushionapproximately in a middle horizontal plane of the bearing, for exampleby elastic and form-fitting means such as a tongue and groove.

Another example embodiment comprises an upper ring resting against theupper supporting bearing surface and a lower ring resting against thelower supporting bearing surface whereby a circumferential gap isprovided between the two rings which permits sufficient tiltingmovements of the bearing.

These teachings of the invention have the advantage that the entireheight of the pressure cushion is available for the tiltability whereasthe horizontal displaceability depends on the height of the pressurecushion which is not enclosed by the ring or rings.

Since the resistance or stiffness of the bearing to tilting movements,as distinguished from its movability due to tilting, is likewisedetermined by the height of the circumferential area not enclosed by therings, that is, by the gaps, the invention provides a tiltable bearinghaving small dimensions and a simple structure and nevertheless goodtiltability characteristics while being sufficiently resistant totilting and to horizontal movement.

BRIEF FIGURE DESCRIPTION In order that the invention may be clearlyunderstood, it will now be described, by way of example, with referenceto the accompanying drawings, wherein:

FIG. 1 is a cross section through a tiltable bearing according to theinvention wherein the pressure cushion is surrounded by one ring;

FIGS. 2 to 6 are partial cross sectional views through modifications ofthe tiltable bearing according to FIG.

FIG. 7 is a cross section through a sliding or gliding bearing accordingto the present invention;

FIG. 8 shows a preferred embodiment of a fixed bearing with an annularcushion;

FIG. 9 is a cross section through a sliding bearing with an annularcushion and arranged permitting sliding in one direction only; I

FIG. 10 is a cross section through a tiltable bearing with twocircumferential rings rather than one;

FIGS. 11 and 12 illustrate modifications of the tiltable bearing of FIG.10, in cross section, whereby the embodiment of FIG. 12 includesreinforcing inserts;

FIG. 13 is a cross section through a bearing that is slidable andtiltable and which has two circumferential rings;

FIG. 14 illustrates a cross section through a movable sliding bearingwith two circumferential rings whereby the bearing is movable in apredetermined direction; and

FIG. 15 is a fixed bearing with two inner and outer circumferentialrings each.

DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS OF THE INVENTION In thedrawings the same reference numerals have been used for designating thesame or corresponding parts.

The tiltable bearing shown in FIG. 1 comprises a pressure cushion l, forexample made of rubber or plastic material, and a ring 2, for examplemade of steel, surrounding the cushion. Upper and lower supportingbearing surfaces 3 and 4 respectively are formed by the supportingstructure, for example a bridge member 5 and a foundation member 6bearing or resting against the pressure cushion. The ring 2 is providedwith a circumferential groove 7 approximately in a plane extendinghorizontally through the middle of the ring. A circumferential rib 8around the pressure cushion 1 forms a tongue which engages the groove 7in a form-fitting manner. Thus the ring 2 is rigidly secured to thepressure cushion 1.

However, outside the tongue and groove engagement, the pressure cushionl rests elastically and slidingly against the inner circumferentialsurface 11 of ring 2. Surface 11 is substantially cylindrical. Since thering 2 is secured to the pressure cushion l merely by the groove 7 andtongue or rib 8 and since a gap 9 is provided between the ring and themembers 5 and 6 of the supporting structure, ring 2 may move freely withrespect to the supporting structure when the bearing is under load bythe supporting structure.

When the pressure cushion is deformed sliding movements occur at theinner circumferential surface 11 of the floatingly supported ring 2.These sliding movements merely slightly impede the free sheardeformation of the pressure cushion l in the area of its circumference.The inner edges of the ring 2 are rounded in order to prevent damage tothe pressure cushion in the vicinity of said inner edges. Preferably,the pressure cushion l is a circular disk, however, it may have anydesired and suitable shape, for instance a polygonal shape. The innercircumferential surface 11 of ring 2 is fitted to the outercircumferential surface of the pressure cushion l. The outercircumferential surface of ring 2 may be geometrically similar to theinner circumferential surface 11, but this is optional and the outercircumferential surface of the ring 2 may have any desired shape, thatis it may be, for instance, rectangular or polygonal.

The form-fit between the pressure cushion 1 and the ring 2 whichoperates as a self centering of the ring relative to the pressurecushion, may be accomplished by curved circumferential surfaces on thering as well as on the pressure cushion, for instance by making thesesurfaces concave or convex as viewed relative to a vertical plane,whereby a relative movement between the marginal or circumferentialareas of the pressure cushion with respect to the inner circumferentialarea of the ring is made possible along the entire width of the ring.

The pressure cushion 1 shown in FIG. 2 has a cross sectional, convexcircumferential surface whereas the ring 2 has a correspondingly curvedconcave inner circumferential surface 1 l a. Due to these curvedsurfaces, the ring is attached to the pressure cushion in a form fittingmanner. In addition, a further form-fit may be provided in the centralplane of the ring. More specifically, in FIG. 2 this is realized by acircumferential groove 7a in the ring 2 and a circumferential rib 8a onthe pressure cushion 1 fitting into the groove. The curvature of thesurfaces may be selected in accordance with the tilting movement of thesupporting structure that is to be expected in practice. The ring 2 ofFIG. 2 has a greater vertical height then the pressure cushion 1. Theupper and lower bearing surfaces 3a and 4a respectively of thestructures 5a and 6a of the load and foundation rest on the pressurecushion 1. Therefore, these supporting surfaces 3aand 40 extend into thering 2 sufficiently to form a gap 9a so that the free movement of thering 2 is assured. The embodiment of FIG. 2 permits a rather smallhorizontal movement of the bearing since the circumference of thepressure cushion 1 is almost completely supported by ring 2. On theother hand, the entire height of the pressure cushion is available forits tiltability due to the the gaps 9a above and below the ring 2. Thewidth of the gaps 9a determines the extent of the tilting movement.

FIG. 3 shows the slidable bearing according to the invention. A slidinglayer 12 is embedded preferably in the upper, outer surface of thepressure cushion l. The sliding layer 12 is slidably movable on asliding plate 13 of the adjacent structure 5. The ring 2 has a convexcross sectional surface, where it faces the pressure cushion 1 whereasthe latter is provided with a respective concave circumferentialsurface.

It is to be understood that the circumferential surface of the pressurecushion in the embodiment of FIG. 2 as well as of FIG. 3 may be straightor cylindrical in cross section whereby a corresponding curvature orindentation of the circumferential surface will result when the cushionis pressed by the load against the inner circumferential surface 11a or11b of the ring 2 respectively.

The bearing according to FIG. 4 has a convexly curved innercircumferential surface 11b. The circumferential surface of the pressurecushion lb is provided with a reinforcement la having a higher modulusof elasticity. The reinforcement la forms also a ring which in thisembodiment rests at the top and bottom side of the pressure cushion lbagainst plates 14 and 15 which are large enough to cover the cushionproper as well as the reinforcement la. This reinforcement assures thatthe pressure cushion 1b will not be squeezed out of the gaps 9, 9abetween the ring 2 and the upper and lower supporting structure 5 and 6.In addition, the reinforcement 1a further improves the resistance of thebearing against horizontal displacements. In the embodiment of FIG. 4,the reinforcement la extends all around the circumferential surface ofthe pressure cushion lb. However, these reinforcements may in otherembodiments extend only in the area of the gaps 9, 9a. Both types ofreinforcements may, tola certain extent, contribute to a transfer of thehorizontal force by the hearing. Incidentally, the plates 14, 15cooperate with the ring la in the overall reinforcement of the pressurecushion lb. These plates l4, 15 may be rigidly attached to the cushionproper or a form-fit may be provided between the cushion and theseplates.

FIG. 5 shows an advantageous combination of the bearing according to thepresent invention with customary structural forms. The pressure cushionl is provided with reinforcing plates 21, 22 and 23, 24 in its regionsoutside of the ring 2. This location of the plates 21 to 24 in regionsoutside the confinement by the ring 2, permits a displaceability in adirection perpendicularly to the axis of the bearing. On the other hand,the regions outside the ring and particularly the region inside the ring2 permit for the tilting and rotation. Especially the region within thering 2 contributes to this movability since no reinforcement plates areprovided in this area so that it may be deformed by shearing forces tothe fullest extent.

The bearing according to FIG. 5 is further provided with a sliding layer2a between the inner circumferential surface of the ring 2 and thecushion proper. This sliding layer 2a improves the sliding of thecircumferential areas of the pressure cushion on the ring 2, whereby abetter shearing deformation of the pressure cushion in these areas isaccomplished. Such sliding layer 2a may be provided on all theembodiments shown in the drawings not just in the embodiment of FIG. 5.

A particular advantage of the sliding layer 2a is seen in that it servesas a separating layer during the production of the bearing. If the layer2a is made of a suitable separating material, the pressure cushion 1 maybe directly vulcanized into the ring 2 or it may be hardened directlywithin the ring 2 without running the risk that the pressure cushionadheres to or becomes glued to the ring 2. The reinforcing plates 22 and23 may also extend into the ring 2 or rest against the same, however,the arrangement has to be such that they do not interfere appreciablywith the tiltability of the bearing. Preferably, the sliding layer 2a isdirectly secured to the ring 2.

As a modification, instead of providing a sliding layer 2a, the ringsmay be made of a synthetic material which is preferably reinforced byfibers, such as glass fibers whereby the synthetic material is selectedto have the desired sliding characteristics. However, metallic orsynthetic material rings may also be used and provided with a metal orother coatings which are formed or selected to provide a corrosionresistant and sliding layer.

In the embodiment according to FIG. 6, an area 1d, which completelyenvelopes the pressure cushion l, is reinforced. In such a structure,the interior of the pressure cushion may have plastic characteristicswhereby the plastic deformation may change into an elastic deformationtoward the outer regions of the cushion.

In view of the foregoing, it will be appreciated that the tiltablebearings according to the present invention may be constructed assliding bearings. For instance, a sliding plate may be provided whichslidably rests against one of the supporting surfaces and which isconnected to the pressure cushion in a rigid or a form-fit manner and,if desired, the glide plate or plates may extend into adjacent areas ofthe ring.

The sliding plate may be guided in the adjacent supporting surface sothat it permits a sliding movement in one direction only as isillustrated, for example, in FIG. 7, wherein a portion 31a of a slideplate 31 covering the pressure cushion 1 extends into a recess of theupper supporting structure. The plate 31 reaches with its outercircumference into the ring 2 and rests against the innercircumferential area of the ring. The portion 31a of plate 31 isslidingly guided and rests against guiding surfaces 5b and 5c of saidrecess in the supporting structure having side walls lined with slidinglayers 34a and 34b which act as guiding surfaces and permit the slidingmovement only in one direction, namely perpendicularly to the plane ofthe drawing.

In addition, the top surface of plate 31 which forms an annular areaaround the portion 31a is covered with a sliding layer 33 which restsagainst the supporting surface 3 of the structure 5. The bottom side ofthe bearing cushion l is provided with a plate 32 which likewise extendsinto and engages the inner circumferential surface of the ring 2. Plate32 may be connected to the supporting structure 6 in a form-fit manner.This hearing is capable of transmitting horizontal forces in onedirection and to yield in a direction extending perpendicularly to saidone direction because of the rail-like guiding surfaces 5b and 5c. Ifthe bearing is to be rotatable about a central axis only, the portion31a of the plate 31 and the guiding surfaces 34 will be cylindrical.

In another embodiment of the present invention shown in FIG. 8, thepressure cushion has an annular shape, the inner circumference of whichmay be supported by one ring or by two rings extending over a part ofthe height of the ring 2. One or two holding bolts connected to thesupporting structure may reach into the inner ring or rings supportingthe inner circumference of the annulus for securing the bearing in afixed position. If in these embodiments only one holding bolt extendingfrom one bearing surface is provided, this one bolt may be held in aguiding means in the supporting structure for permitting a shift ordisplacement of the bearing.

Referring further to FIG. 8, the annular pressure cushion 35 is insliding contact at its inner circumferential surface with an inner ring36. Thus the bearing of FIG. 8 is constructed as a fixed bearing. Theinner ring 36 is held by the pressure cushion in a form fitting mannerin the same way as the ring 2 carried by the outer circumferentialsurface of the pressure cushion 35. Bolts 37 and 38 secured to thesupporting sructures 5 and 6 extend from both sides into the inner ring36 thereby leaving a gap 39 between the ring 36 and bolts 37, 38 forpermitting the free movability of the ring 36. A gap 40 is further leftbetween the end faces of the bolts 37 and 38 so that the bearing mayalso be vertically displaced. The bolts may be made of an elasticallyyielding material or elastically yielding intermediate layers may beplaced into the gap 38 between the bolts and the inner ring.

The bearing of FIG. 9 is constructed as a sliding bearing in a mannersimilar to that of the bearing illustrated in FIG. 7 to permit a slidingmovement of the upper structure with respect to the lower structure butin one direction only. An annular pressure cushion 35 is provided whichis supported at its inner circumference by an inner ring 36. A bolt 38extends into the inner ring 36. The bolt 38 is provided adjacent to itsupper portion 41 with two parallel guiding surfaces which extend into aguiding groove 42 in the upper structure 5. Between the guidingsurfaces'of the bolt 38 and the side walls-of the groove 42 there arelocated sliding layers 34a and 34b. The guiding groove 42 extendsperpendicularly to the plane of the drawing and has a depth sufficientto leave a gap above guiding portion 41 of bolt 38 to permit the innerring 36 toadjust itself freely in the vertical direction.

In still another embodiment of the invention two confining rings may beused. One of the advantages of this embodiment is that the two ringsengage the bearing surfaces of the supporting structures and are securedto these structures to permit a better connection of the bearing tothese supporting surfaces. At least the inner surface of the upper ringwhich faces the pressure cushion may flare outwardly but toward a centerextending horizontally through the pressure cushion to thereby describe,for instance, a frusto-conical-circumferential surface. Such a shape ofthe inner surface of the rings provides a good hold of the rings on thepressure cushion and accommodates the deformation behavior of thepressure cushion under a load.

Referring to FIG. 10, the tilting bearing shown therein comprises againa pressure cushion 1 which is supported on its outside by an upper ring16 and by a lower ring 17 which rest against the upper and lowersupporting surface of the supporting structures 5 and 6 respectively. Agap 18 is left between the rings 16 and 17 to permit tilting movementsand corresponding small horizontal displacements of the bearing when thepressure cushion is deformed. In the vicinity of the gap, the pressurecushion has a circumferential groove which becomes narrower in thevertical direction when a load is applied to the bearing. In order tocontrol the deformation of the cushion in the area of the rings 16 and17, the interior ring surfaces which contact the pressure cushion areinclined outwardly and widened in the direction toward the gap 18.

At least one of the two rings 16 or 17 may be rigidly connected to therespective supporting surface, for instance, by a form-fit between thering and said supporting surface. Such a form-fit may be achieved by aplate or shoulder which is anchored in the supporting surface and whichextends into the ring while resting against the inner surface of thering. Advantageously, the plate or shoulder may be rigidly connected tothe ring. Various modifications are available for rigidly connecting oneor both rings to the supporting surface, depending on the type ofbearing and the type of load to which the bearing will be subjected.

In the tiltable bearing shown in FIG. 11, the pressure cushion 1 has asurface layer 1d which completely envelopes the pressure cushion and isharder than its core lb. In the vicinity of the gap 18 between rings 16and 17, there is again provided a groove 19 formed in the surface layer1d. The structure members 5 and 6 on the supporting structure haveshoulders 5a and 6a respectively which engage the rings 16 and 17 in aform fitting manner. These shoulders, or one of them, may be platesrigidly secured to the respective structural member and reaching intothe respective ring or being secured thereto. However, the rings mayalso be directly secured, as by welding, to the supporting structure.The embodiment wherein a plate or plates supported by the respectivestructural member reaches into the confining ring to which it is alsosecured is especially suitable for constructing a gliding bearing,whereby a glide layer may be embedded in the plate or in the plate andin the ring which glide layer cooperates with a glide plate of therespective supporting surface.

The horizontal movability of the tiltable bearing according to theinvention may be restricted further by increasing its resistance toshearing forces in the area of areas of the pressure cushion which arenot surrounded by the ring or rings as compared to the enclosed areas ofthe pressure cushion. This may be done,for instance, by reinforcementlayers or by reinforcing the circumferential zones of the pressurecushion that are not enclosed by the rings.

Such an arrangement is shown in FIG. 12 in which reinforcement layers 20are provided within the pressure cushion l in the area between the rings16 and 17, opposite the gap 18. These reinforcements may be platesextending parallel to the bearing surfaces 3 and 4. These reinforcementlayers 20 in the area of gap 18 control the shear deformation ofpressure cushion 1 depending on the load, whereas the areas outside ring16 and 17 permit a tilting or rotating about horizontal axes.

FIG. 13 shows a slidable bearing in which a plate 31 of a slidingmaterial, such as polytetrafluorethylene (PTFE), is inserted in theupper ring 16 which itself is convered by a layer 25 of the samematerial. A sliding plate 13 is provided at the bearing surface 3 andcooperates with the layer 25 and with the plate 31. The lower ring 17rests against the other bearing surface 4 through a layer 26 made of amaterial having only a relatively low elastic deformability. A plate 34is inserted into the ring 17 and rests on the bearing surface of thesupport structure 6. The glide plate 32 is anchored in the bearingsurface of the supporting structure 6 by bolts 27. In addition to thegroove 19 in the pressure cushion 1 in the area of the gap 18 there arefurther grooves 26' provided in the area of the upper and lower edge ofthe pressure cushion.

FIG. 14 shows a slidable and tiltable bearing which is slidable only inone preferred direction, in this instance, the direction extendingperpendicularly to the plane of the drawing. For this purpose, the uppersupporting surface 28 is extended to form a channel with supporting sidewalls 30 which confine the rings 16a and 17a for movement only in saidone direction. Between the rings 16a and 17a there are arranged slidinglayers 29 against which the rings 16a and 17a rest in a sliding manner.A sliding plate 31a extends into the upper ring 16a. The plate 31aextends over the top of the ring 16a and rests slidably against thesupporting surface 28. Similar to the arrangement according to FIG. 13,the lower ring 17a is provided with a plate 32 extending into the lowerring and fixed with respect to the lower supporting surface 4.Preferably, rings 16a and 17a have a straight or cylindrical outercontour.

FIG. 15 illustrates a fixed bearing with an annular cushion 10 as inFIGS. 8 or 9. In addition to the outer rings 16 and 17, inner rings 43and 44 are provided in the annular pressure cushion 1c so that thecushion rests laterally against the inner and outer rings. A bolt 45extends with play into the inner rings 43 and 44. Bolt 45 is supportedby the structural members 5 and 6 by means of elastic layers 46 and 47respectively. If said play between bolt 45 and the inner rings 43, 44 issufficiently small horizontal forces may be transmitted by the bolt 45from inner ring 44 to inner ring 43.

The features of the bearings of FIGS. 14 and 15 may be combined toconstruct a bearing for permitting displacement in one direction only inwhich the inner bolt 45 transmits horizontal forces from the inner ring43 to the other inner ring 44. In this arrangement, the displacement ofthe structural members 5 and 6 with respect to each other is limited tosaid one direction and in addition the tilting movement is controlled totake place solely in a direction extending parallel to said onedirection.

The bearing according to FIG. 15 may also be constructed in accordancewith the features mentioned in connection with FIG. 9 whereby the bolt45 would be guided in one or the other of the members 5, 6 so as toslide in a preferred direction.

As will be evident from the above, various modifications of the presenttiltable bearings are possible. For example, the features of thebearings described in connection with FIGS. 1 to 9 may be employedsingly or bined with heretofore known bearings and the princi-- ples onwhich they are based. The circumferential area enclosed by the ring orrings may also be smaller than half the height of the pressure cushion.The present bearings may be easily adapted to the various requirementsof a supporting structure, i.e., the present bearings may be used eitheras a pure tilting bearing or as a fixed bearing or as a slidablebearing. Where reinforcements are embedded in the cushion regions notconfined by said ring or rings, the gaps 9, 9a or 18 may generally belarger than without these reinforcements.

In view of the foregoing, it is to be understood that it is intended tocover all modifications and equivalents within the scope of the appendedclaims.

What is claimed is:

1. In a tiltable fearing for heavy structures wherein a pressure cushionis arranged between an upper bearing surface forming part of said heavystructure and a lower bearing surface forming part of a supportingstructure, whereby a given spacing is provided between said bearingsurfaces, said pressure cushion having a circumferential surface, anupper wall facing said upper bearing surface, and a lower wall facingsaid lower bearing surface, said circumferential surface of the pressurecushion connecting said upper and lower walls of the cushion; theimprovement comprising cushion confining upper and lower ring memberseach having an inner surface surrounding at least a portion of saidcircumferential cushion surface, said upper and lower ring membershaving a combined height less than said given spacing to provide a gaptherebetween of sufficient height to permit a tilting movement, said gapbeing simultaneously sufficiently small in height for controllinghorizontal displacements of the bearing, and means for providing aform-fit between said inner surfaces of the ring members and saidcircumferential surface of said pressure cushion, said form-fit meanspermitting a relative gliding movement between the inner surfaces of thering members and the circumferential cushion surface.

2. The tiltable bearing according to claim 1, wherein saidcircumferential cushion surface has a given height, said ring numbersmeans, having a total height corresponding-to more than one half of saidgiven cushion height.

3. The tiltable bearing according to claim 1, wherein at least saidupper ring member comprises an inner surface facing the pressurecushion, which surface widens toward the gap.

4. The tiltable bearing according to claim 1, wherein said means forsecuring said ring members comprise means for rigidly connecting atleast one ring member to its respective bearing surface.

5. The tiltable bearing according to claim 1, wherein at least one ofsaid bearing surfaces comprises means for reaching with a form-fit intothe respective ring menber.

6. The tiltable bearing according to claim 15, further comprising platemeans, means for anchoring said plate means to the respective bearingsurface, said plate means reaching into the respective ring and restingagainst the inner surface of the ring.

7. The tiltable bearing according to claim 6, further comprising meansfor rigidly connecting said plate means to the respective ring.

8. The tiltable bearing according to claim 1, wherein the pressurecushion comprises groove means in its circumferential surface.

9. The tiltable bearing according to claim 1, wherein the pressurecushion is annular and wherein said ring means comprise an upper outerring, an inner outer ring, an upper inner ring, and a lower inner ring,said annular pressure cushion having an inner circumferential surfaceagainst which the inner rings rest to provide a further gaptherebetweeen, said further gap substantially registering with saidfirst mentioned gap.

10. The tiltable bearing according to claim 9, further comprising meansfor rigidly connecting at least one of said rings to the respectivebearing surface, a bolt, means for elastically supporting said bolt atits top and bottom sides against the respective bearing surface,

said bolt being located with play within said inner rings.

relative to one bearing surface, said slidable supporting meanscomprising a layer preferably made of polytetrafluorethylene.

12. The tiltable bearing according to claim 1, comprising a bearingsurface having two opposite parallel side walls, said pressure cushionand rings being slidably supported with respect to said side walls.

13. The tiltable bearing according to claqim 1, furth'er comprisingreinforcing plate means in said pressure cushion, said plate means beinglocated in a region of the pressure cushion registering with said gap.

14. The tiltable bearing according to claim 1, further comprisingsliding surface means located between the ring means and the adjacentcircumferential surface of the pressure cushion, said sliding surfacemeans being connected to the ring or rings.

15. The tiltable bearing of claim 1, wherein said upper and lower ringmembers have a total height, as viewed in a direction perpendicular tosaid bearing surfaces, corresponding to at least one half of said givenheight of said pressure cushion.

16. The tiltable bearing of claim 1, further c0mprising means forsecuring said upper and lower ring members to the respective bearingsurfaces.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,782,788 Dated JanualjLl. 197 i Invent0 Waldemar Koester e1: 21

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 9, line 20 "fearing" should read --bearing-- Column 9, line 47"numbers means" should read -members-- Column 10, line t ."menber"should read -member-- Column 10, line 5 "claim 15" shouldread --claim5-- Column 10, line &0 "claq'im 1" should read --claim 1-- Signed andsealed this 9th day of April 1974'.

(SEAL) Attest:

EDWARD I=I.FLETCHER,JR. C. MARSHALL. DANN Attesting Officer Commissionerof Patents

1. In a tiltable bearing for heavy structures wherein a pressure cushionis arranged between an upper bearing surface forming part of said heavystructure and a lower bearing surface forming part of a supportingstructure, whereby a given spacing is provided between said bearingsurfaces, said pressure cushion having a circumferential surface, anupper wall facing said upper bearing surface, and a lower wall facingsaid lower bearing surface, said circumferential surface of the pressurecushion connecting said upper and lower walls of the cushion; theimprovement comprising cushion confining upper and lower ring memberseach having an inner surface surrounding at least a portion of saidcircumferential cushion surface, said upper and lower ring membershaving a combined height less than said given spacing to provide a gaptherebetween of sufficient height to permit a tilting movement, said gapbeing simultaneously sufficiently small in height for controllinghorizontal displacements of the bearing, and means for providing aform-fit between said inner surfaces of the ring members and saidcircumferential surface of said pressure cushion, said form-fit meanspermitting a relative gliding movement between the inner surfaces of thering members and the circumferential cushion surface.
 2. The tiltablebearing according to claim 1, wherein said circumferential cushionsurface has a given height, said ring members having a total heightcorresponding to more than one half of said given cushion height.
 3. Thetiltable bearing according to claim 1, wherein at least said upper ringmember comprises an inner surface facing the pressure cushion, whichsurface widens toward the gap.
 4. The tiltable bearing according toclaim 1, wherein said means for securing said ring members comprisemeans for rigidly connecting at least one rIng member to its respectivebearing surface.
 5. The tiltable bearing according to claim 1, whereinat least one of said bearing surfaces comprises means for reaching witha form-fit into the respective ring menber.
 6. The tiltable bearingaccording to claim 15, further comprising plate means, means foranchoring said plate means to the respective bearing surface, said platemeans reaching into the respective ring and resting against the innersurface of the ring.
 7. The tiltable bearing according to claim 6,further comprising means for rigidly connecting said plate means to therespective ring.
 8. The tiltable bearing according to claim 1, whereinthe pressure cushion comprises groove means in its circumferentialsurface.
 9. The tiltable bearing according to claim 1, wherein thepressure cushion is annular and wherein said ring means comprise anupper outer ring, an inner outer ring, an upper inner ring, and a lowerinner ring, said annular pressure cushion having an innercircumferential surface against which the inner rings rest to provide afurther gap therebetweeen, said further gap substantially registeringwith said first mentioned gap.
 10. The tiltable bearing according toclaim 9, further comprising means for rigidly connecting at least one ofsaid rings to the respective bearing surface, a bolt, means forelastically supporting said bolt at its top and bottom sides against therespective bearing surface, said bolt being located with play withinsaid inner rings.
 11. The tiltable bearing according to claim 1, furthercomprising means for slidably supporting the bearing relative to onebearing surface, said slidable supporting means comprising a layerpreferably made of polytetrafluorethylene.
 12. The tiltable bearingaccording to claim 1, comprising a bearing surface having two oppositeparallel side walls, said pressure cushion and rings being slidablysupported with respect to said side walls.
 13. The tiltable bearingaccording to claim 1, further comprising reinforcing plate means in saidpressure cushion, said plate means being located in a region of thepressure cushion registering with said gap.
 14. The tiltable bearingaccording to claim 1, further comprising sliding surface means locatedbetween the ring means and the adjacent circumferential surface of thepressure cushion, said sliding surface means being connected to the ringor rings.
 15. The tiltable bearing of claim 1, wherein said upper andlower ring members have a total height, as viewed in a directionperpendicular to said bearing surfaces, corresponding to at least onehalf of said given height of said pressure cushion.
 16. The tiltablebearing of claim 1, further comprising means for securing said upper andlower ring members to the respective bearing surfaces.